A cigarette hopper comprises at least one substantially vertical channel, which receives the cigarettes from a top feed conduit and feeds them by force of gravity to a number of outlets at the bottom of the hopper, where a number of pushers expel groups of cigarettes cyclically from the outlets onto a packing line.
Depending on market demand, the same packing machine may be used to pack different types of cigarettes, normally differing in size (length and/or diameter) or in the characteristics of the tobacco or filter.
To switch over to a new type of cigarette (i.e. at each brand change), the hopper must be cleared of the old brand and filled with the new one. Filling of the hopper must be conducted in controlled manner, in the sense that the cigarettes must be placed inside the hopper in orderly manner and with no undue mechanical stress which might damage the cigarettes (particularly as a result of tobacco fallout from the tips). At present, the hopper is filled manually, i.e. by an operator starting from the bottom and working upwards until the hopper is almost full; and only then can the cigarettes be fed in from the top feed conduit.
Filling the hopper manually is an extremely slow job, obviously requiring the assistance of an operator, so that preparing the packing machine for a new brand involves considerable downtime.
Patent DE684851 describes the controlled filling of a cigarette box using a flexible belt which accompanies the cigarettes during the controlled filling of the cigarette box.
Patent US6540061B1 describes the controlled filling of a cigarette box or hopper. The cigarettes are fed by force of gravity and slide inside separate compartments. As they are fed in, the cigarettes are supported underneath by mechanical supports, which are eased downwards to gradually increase the volume of the compartments until a maximum volume is reached. On reaching the bottom of the box or hopper, the mechanical supports are moved horizontally out of the box or hopper and back up to the start position. In an alternative embodiment for filling a cigarette hopper, a guide member is positioned at the top of the hopper to intercept and support the incoming mass of cigarettes, and is then moved gradually to ease the cigarettes in, and eventually out of the hopper. The guide member is comb-shaped and is moved in and out of the hopper through a comb-shaped wall of the hopper.
Patent US5743067A1 describes a cigarette box filling device, wherein a cigarette hopper has an output opening defined by the outlets of a number of side by side channels for respective columns of cigarettes. The hopper has a box filling device having a horizontal plate for supporting an orderly mass of cigarettes, and which moves vertically along a box, positioned with its inlet facing the output opening, and has side by side seats on top for respective cigarettes. Each outlet faces a rib separating two respective adjacent seats on the plate, and the channels all slope the same way with respect to the plate.
Patent US4366895A1 describes a device for filling a cigarette box divided internally into channels by parallel vertical walls; and the device comprises a number of horizontal supporting members, each for supporting and easing the cigarettes downwards into a respective channel.
The filling devices described above all employ a supporting member for easing in the mass of cigarettes, and which is extracted from the channel once it is full. Since the cigarette feed channel must be sealed off as far as possible from the outside, to prevent uncontrolled escape of the tobacco powder inevitably produced by the cigarettes, extracting the supporting member from the channel once it is full poses various construction problems.
Moreover, the filling devices described above, by employing a large, heavy, rigid supporting member, are bulky and so call for high-performance (i.e. bulky, high-cost) actuators.